Download May 2017 - Museums Wellington

What’s up in Space?
May 2017 The Brightest Stars in the Sky
The chart is oriented for
April 15 at 10pm NZST
May 1 at 9pm NZST
May 15 at 8pm NZST
June 1 at 7pm NZST
Our evening skies this month are dominated by Jupiter and
Saturn, along with some of our brightest stars. Jupiter will
be one of the first objects to appear, visible in the north east
shortly after the Sun has set.
Just to the right of Jupiter is Spica, the brightest star in the
constellation of Virgo, and below, just above the horizon is
orange coloured Arcturus, the brightest star in the northern
celestial hemisphere and the 4th brightest in the night sky.
Arcturus has a similar mass to the Sun, but has already
expanded to become a red giant, with 25 times the diameter
and 170 times the luminosity of our own star. When close to
the horizon it often appears to twinkle red and green as its
light is broken up by our atmosphere.
All three brighter stars are in the southern hemisphere, and
are also visible in our evening skies this month. The brightest,
Sirius, sits halfway up the western sky, with Orion’s belt, now
almost vertical, below. Rigel and Betelgeuse, the seventh
and ninth brightest stars sit to either side of the belt. Both
Orion and Sirius will soon disappear from our evening skies,
before reappearing just before the Sun in the morning over the
coming months.
The second brightest star, Canopus, is circumpolar here in New
Zealand, never dropping below the horizon. This month it sits a
little higher than Sirius, further around towards the south west.
To complete the trio, the third brightest star, Alpha Centauri is
high in the south east, pointing the way to the Southern Cross.
Below Alpha Centauri, rising in the twilight sky, is the curve of
stars marking our winter constellation, Scorpius/ Te Matau a
Māui. Its brightest star, Antares/Rehua, is a variable star and is
on average the 15th brightest in the night sky. Antares, one of
the largest stars known, is a red supergiant almost 900 times
the diameter of the Sun. If it were placed at the centre of the
Solar System, its surface would extend to the middle of the
asteroid belt.
Below Antares, and rising a little later in the evening, is bright,
cream coloured Saturn. It’s a great time to observe Saturn
through a small telescope this month, with its rings close to
maximum tilt.